Trade unionists who protest against job cuts or paramilitary killings could face up to six months in prison under proposed Northern Ireland parades legislation, workers said.
Demonstrators outside workplaces, as well as rallies such as those against the shooting dead of two soldiers and a policeman last year, could be required to give 37 days' notice, according to the plans.
A special meeting to support the campaign against the Draft Public Assemblies, Parades and Protests Bill will be held on Thursday night in Belfast.
A spokesman for the organisers said: "The new legislation will severely restrict the ability of trades unionists, political activists, community and campaign groups to organise effective and spontaneous public demonstrations to highlight issues which often require a speedy and immediate public response at very short notice.
"Protest meetings such as those against the wars in Iraq and Afghanistan, solidarity vigils held to support the victims of racist attacks, or demonstrations such as those outside the BBC in relation to airtime being given to the BNP will all fall under the remit of the new law."
Gatherings involving 50 or more people in public would be required to give 37 days' notification of their intention to hold the gathering.
The legislation is designed to create a new and improved framework to rule on controversial loyal order marches, including a focus on local solutions, mediation and adjudication.
Nationalist residents in areas such as north Belfast and Portadown in County Armagh oppose Orange Order processions in their areas because they view them as triumphalist.
Members of the loyal orders accuse residents of going out of their way to be offended and maintain it is their traditional right to demonstrate on the streets.
Thursday's meeting will feature introductions from Patricia McKeown, Regional Secretary of Unison, NIPSA General Secretary Brian Campfield and Barbara Muldoon from the Anti Racism Network.